1. Field of the Invention
This invention relates to firearms and more particularly to a firearm of the automatic or semiautomatic type having a mechanical recoil movement delaying mechanism which delays breech opening until gas pressure drops to a safe level.
2. Description of the Prior Art
Automatic and semiautomatic firearms of the type having a reciprocating breechblock, or slide, function on a long established well known principle in which forward, or loading, movement of the breechblock will pick up a single cartridge from the weapon's magazine, load the cartridge into the firing chamber and close the breech. Subsequent to firing, the breechblock moves backward, or recoils, and such recoil movement extracts the empty cartridge case from the firing chamber, ejects it from the weapon and simultaneously cocks the hammer.
In this type of reciprocating breechblock action, it is necessary to provide some means for delaying recoil movement of the breechblock subsequent to firing to allow gas pressure in the weapon's firing chamber to drop to a safe level. Typically, breechblock mechanisms fall into two commonly used categories and a third less commonly employed category.
The first commonly used type of reciprocating breechblock mechanism is referred to as a blowback operated mechanism. Briefly, in firearms operating on the blowback principle, the mass of the breechblock in conjunction with a recoil spring are employed to retard the backward thrust of the fired cartridge case, and thus, delay breech opening long enough to allow the gas pressure in the firing chamber to drop to a safe level. This operating principle is usually employed only on weapons firing low to medium powered cartridges, in that a larger more powerful cartridge with higher gas pressure would require heavier breechblocks and recoil springs, and those factors defeat the purpose of keeping such firearms as lightweight and compact as possible.
The second commonly used type of reciprocating breechblock mechanism is referred to as a locked breech mechanism. In firearms operated on the locked breech principle, the breechblock and the barrel, having the firing chamber therein, are mechanically locked together during firing and are unlocked, usually by recoil or gas pressure, subsequent to the firing. In weapons that are unlocked by recoil, the mechanically locked breechblock and barrel recoil as a single entity subsequent to firing for a predetermined distance, and will be unlocked when the barrel or breechblock moves into contact with some form of decoupling device such as a deflecting cam surface formed in the weapon's receiver or frame. When the barrel or breechblock contacts the decoupling device, the breechblock is then unlocked and will continue to recoil until the breech is opened. Weapons operating on the recoil principle are relatively costly to manufacture and are relatively complex due to the configurations of the various types of mechanical locking devices and decoupling devices and the costs for machining those devices.
In weapons that are unlocked by gas pressure, the breechblock, or bolt, is mechanically locked to the barrel to close the breech, such as by inclined or cam surfaces which cause the bolt to be deflected or rotated into engagement with locking grooves or the like formed in the weapon. A spring biased piston is coupled to the breechblock or bolt, and subsequent to firing of the weapon, expanding gas pressure is ported to move the piston in a manner so that it unlocks the bolt so that it is free to recoil thus opening the breech. As was the case with weapons that are unlocked by the recoil principle, weapons that are unlocked by gas pressure are relatively expensive to manufacture and are relatively complex due to the configurations of the various types of mechanical locking devices and the costs for machining those devices.
In either case, the locked breech operating principle is normally used only on relatively large weapons which fire medium to high power cartridges in that the mass, weight, complexity and costs of locked breech mechanisms makes their use on relatively small weapons firing medium to low power cartridges impractical and unnecessary.
The third less commonly employed type of reciprocating breechblock mechanism is referred to as a half locked, retarded blowback or hesitation blowback action. In this third operating principle, the mass of the breechblock and the biasing of the recoil spring are employed in conjunction with some form of mechanical delaying means which must be overcome before recoil movement of the breechblock can commence. Such delaying means have taken many forms, such as spring biased levers which are in engagement with the breechblock, and in general the complexity, mass, and the like, of such devices is responsible for their lack of widespread usage.
From the above, it will be seen that the various types of breechblock mechanisms have been designed to suit the power of the cartridges fired, and these mechanisms in turn are a determining factor as to the size, weight, serviceability, cost and complexity of the weapon in which they are used. Therefore, a need exists for a new and useful recoil movement delaying mechanism which, in a first embodiment thereof, allows higher powered cartridges to be used in relatively small and compact automatic or semiautomatic weapons that operate on the blowback principle, and in a second embodiment provides a simple low cost breech locking mechanism for use on relatively large automatic or semiautomatic weapons which operate on the locked breech principle.